1. Field of the Invention
The invention pertains to lock systems with multiple levels of keys.
2. The Prior Art
The subject matter of the parent patent application is a lock system consisting of cylinder locks and appertaining flat keys in which laterally oriented blocking elements are positioned in laterally oriented bores of the rotary cylinder. Said blocking elements sense the profile thickness of an inserted key and, given a predetermined profile thickness, are forced far enough outwardly that their outer ends are level with the perimeter of the cylinder. If the inserted key has a reduced or non-existent profile, an unfilled space is left at the end of the bore. After an initial rotation of the cylinder, a housing pin can fall into the unfilled end of a lateral bore and block further rotation of the cylinder. The fundamental inventive idea therein is that a higher order key exhibits a flat coordination notch at the sensing location of the blocking elements and also exhibits at least one rib at the area of the flat side adjacent thereto. The rib extends laterally from the profile of the key. The rib or ribs are adapted to displace the blocking elements into the position in which they release the cylinder. Further, a lower order key is provided at the same sensing location of the blocking elements with a deep coordination notch, whereby there are no rib or ribs extending laterally from the profile of the key. The core pin allocated to said coordination notch has an upper offset piece and an appertaining shank whose diameter corresponds to the thickness of the lateral ribs of the higher order key at the sensing location, whereby this shank, just like the ribs, is adapted to displace the blocking elements into the position which releases the cylinder.
A significant feature of the subject matter of the invention of the parent patent application consists therein that the blocking elements are formed of blocking pins which exhibit offset sensing ends whose thickness corresponds to the length of the offset core pin piece in addition to its point, and that the diameter of the pin shanks corresponds to that of the allocated housing pin.
A lock system is achieved by means of the invention of the parent patent application in which the higher order keys are largely secured against copying. In order to make such a higher order key from a lower order key, in contrast to standard copying methods based on removal of material, material would have to be applied in order to fill the deep notch of the lower order key in the direction of a flat notch and the formation of one or more lateral profile ribs.
Protection against copying flat keys provided with profile is already the subject matter of the German LP No. 2,059,523 whose main inventive idea is to be viewed therein that at least one additional longitudinal rib projecting beyond the lateral surface of the flat key is provided, by means of which additional longitudinal rib an additional locking blocking pin is actuated. The lock can be actuated when the additional longitudinal rib exhibits a predetermined height which displaces the additional blocking pin far enough toward the outside of the cylinder that it completely fills its cylinder core bore in addition to a preceding counter-sink which may be present. The blocking pin so displaced does not allow the allocated housing pin to spring into the bearing bore of the blocking pin or, respectively, the counter-sink after an initial rotation of the cylinder core and prevent further rotation of the cylinder core.
According to a further feature of the lock device of the German LP No. 2,059,523, two additional longitudinal ribs are provided which project from the opposite lateral faces of the flat key and are each sensed by an additional blocking pin.
As in the subject matter of the parent patent application, the advantage connected with this key is that the key is protected against copying since its manufacture from commercially available blanks requires the addition of material in order to be able to form the additional longitudinal ribs projecting over the key profile. This feature, as already explained, represents a departure from the usual copying method by means of removal of material and which is very difficult for an unauthorized copier.
In order to make the lock device of the German LP No. 2,059,523 tamper-proof by preventing the additional blocking pins, which sense the additional longitudinal ribs from being rendered ineffective by means of manipulation, a lock device consisting of a rotary cylinder lock and an appertaining flat key has been proposed by the German LP No. 2,441,362. The lock of the German '362 patent proceeded from the fact that additional one-piece blocking pins can be arranged in the cylinder core of the lock and at least one additional longitudinal rib projecting laterally from the surface of the flat key is provided at the lateral face of the flat key. The additional longitudinal rib is sensed by the additional blocking pins. These pins, given a flat key which fits, lie in the separating line between the cylinder core and the cylinder housing with its end face facing away from the key channel and allow the continued rotation of the cylinder core after an initial rotation. The primary inventive idea in this case consists of the use of safety blocking pins arranged in front of, as viewed from the key bit, the additional blocking pins. These safety blocking pins sense the recesses of the additional longitudinal ribs and which are opposite the locking recesses, grooves or the like in the cylinder housing. It is these locking recesses, grooves or the like that the safety blocking pins enter when they assume their blocking position.
The resistance to tampering achieved with this lock device is first based on the fact that the safety pins seated in front of the additional blocking pins no longer allow displacement of the additional blocking pins toward the outside of the cylinder by means of a tool. Further, it is based on the fact that every positional displacement of the safety pins toward the outside by means of a tool or the like effects entry of these pins into their housing bores which results in the immediate blocking of the cylinder core against rotation.
The above inventions reveal ways of making keys nonduplicatable and making the locks functioning with them tamper-proof. In the subject matter of the parent patent application as well as in that of the German LP No. 2,059,523, the protection against duplication of keys is achieved in that an addition of material is required in order to duplicate the keys. In the subject matter of the German LP No. 2,411,362, the lock's resistance to tampering is achieved in that safety blocking pins are connected in front of the blocking pins sensing the additional longitudinal rib of the key, whereby the additional longitudinal rib consists of a sequence of elevations and depressions, i.e., is modulated as to height.